Subject: Re: bug#63103: 30.0.50; nconc compiler optimization breaks user packages

From: Mattias Engdegård <[email-masked]>
Date: Thu, 27 Apr 2023 14:28:58 +0200

27 apr. 2023 kl. 12.42 skrev Daniel Mendler <[email-masked]>:

> I think it is
> kind of nice that `nconc' can be used as a tool to turn a proper list
> into an improper list and vice versa.

It's a bit obscure, though --

  (setcdr (last X) nil)

is a lot clearer than

  (nconc X nil)

and when the latter is preferred for performance, a comment might be polite to the reader.

Anyway, a fix has been pushed to master, and the manual entry for `nconc` got an extra example.